also i checked the parts list but i am having problems finding 0.5ft foam wheels with a 4.00mm holeor will i need smaller shaft hole so my motor goes in snuggly.

If you can't find one, remember you can always drill the hole to be bigger. For small robots you can do whats called a press fit, which basically means use force to jam the wheel tight onto the motor output shaft. But for larger robots (like yours) you should use a wheel hub. You attach the hub to your wheel using screws, and your motor shaft goes into the hub.